In General:

The 18th Century:

Johannes Fridericus Alstein Braunius (c. 1708) on the Trinity in General

Further Divisions:

Of the Necessity of the Doctrine of the Trinity

Of the Divinity of Each Person

Overview:

Epistolical Theology:

The 17th Century:

Théodore de Bèze (c. 1605) on the Unity of the Divine Essence, and Three Persons Subsisting therein, Against the Arian Like-Essence Adherents

Dogmatical Theology:

The 3rd Century:

Novatianus of Rome (c. 258) on the Trinity

The 17th Century:

Théodore de Bèze (c. 1605) on the Trinity of Persons and the Unity of Essence

Théodore de Bèze (c. 1605) on the Holy & Unsearchable Trinity

Dialogical Theology:

The 4th Century:

Athanasius I of Alexandria (c. 373) a ‘Dialogue on the Holy Trinity’

Apologetical Theology:

The 17th Century:

Johann a Lent (c. 1696) on the Trinity of Persons in the Divine Essence

Practical Theology:

The 17th Century:

Gisbertus Voetius (c. 1676) on the Utility & Practice of the Doctrine of the Trinity